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The 3rd Generation Partnership Project (3GPP) has released HSDPA, an evolution of the legacy 3G network to provision for data services with variable QoS constraints. Considered as a stepping stone towards B3G, HSDPA can deliver up to 12.8 Mbps data rate. CROSSNET has implemented an HSDPA system level evaluation tool for evaluating RRM protocol performance. Furthermore, cross-layer scheduling and link-adaptation provide key output to enhance the effective capacity and coverage in a more cost effective way; an example of the HSDPA system level evaluation tool is provided in the Figure.
The IEEE 802.11 WLAN (also known as WiFi) technology has seen a high penetration into the Broadband Fixed Wireless Access (BFWA) market to provide data services to hotspot areas, mainly due to ease of network deployment and low cost. However, with the QoS constraints becoming evermore stringent, the IEEE opted to evolve the 802.11 standard to 802.11e, a WLAN technology for QoS support. The key enhancement in this evolved standard can be found in the MAC layer, which now provides support for differentiated service classes, and proposes techniques to enhance the ability of the physical (PHY) layer to deliver time-critical multimedia traffic. CROSSNET is addressing innovative enhancement to the IEEE 802.11e(EDCA), by pursuing research studies on the application of cross-layer signalling to improve QoS delivery, and provide more efficient usage of radio resources by adapting such parameters such as, e.g., arbitrary inter frame spacing, differentiated backoff procedure, and transmission opportunities, as well as acknowledgment policies. A key output from this work is also the development of an event-driven system level simulator for the IEEE 802.11e.
Worldwide Interoperability for Microwave Access (WiMAX) is the commonly used name for broadband wireless access based on the IEEE 802.16 family of standards. WiMAX provides full QoS constrained service types with provisioning for high data rate applications targeted towards wide area coverage, and is widely considered to be a strong competitor to the mobile world. Following wireless trends towards evermore efficient network, CROSSNET designed, implemented and validated advanced scheduling algorithms based on a cross-layer framework architecture, exploiting information between PHY and MAC layer. The scheduling policy, considered pivotal in controlling the trade-off between maximising capacity and QoS delivery, uses cross-layer information to provide preferential treatment to mobile users according to QoS profile, channel conditions, and service classes. A key achievement from CROSSNET is the development of a C++ based mobile WiMAX system simulator that is being used to pursue this line of study. |
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Instituto de Telecomunicações > DEM > Universidade da Beira Interior > Calçada Fonte do Lameiro - Edifício das Engenharias - 6201-001 Covilhã < |
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